investigate PublishString perf

[lts-rad]

while investigating a mem leak issue, a potential cpu perf issue was identified

in a 30s cpu profile

 210ms   runtime/internal/syscall.Syscall6                                              
         syscall.RawSyscall6                                                            
         syscall.Syscall                                                                
         syscall.write     
         syscall.Write (inline)
         internal/poll.ignoringEINTRIO (inline)                                         
         internal/poll.(*FD).Write                                                      
         net.(*netFD).Write                                                             
         net.(*conn).Write                                                              
         google.golang.org/grpc/internal/transport.(*bufWriter).flushKeepBuffer         
         google.golang.org/grpc/internal/transport.(*bufWriter).Flush                   
         google.golang.org/grpc/internal/transport.(*loopyWriter).run                   
         google.golang.org/grpc/internal/transport.NewServerTransport.func2                                                                                                         

this is probably an issue with the grpc starign up a new client each time for sprbus Publish is called